Nathaniel Fujita, 20, faces life in prison without parole if he's convicted in the death of his former girlfriend, Lauren Astley, in July 2011.

Maeghen Reineke, Astley's former manager, described a conversation between Beth Fujita, the defendant’s mother, and Astley in June 2011 at Store 344 at Natick Mall, where Astley worked.

“In this particular conversation, she had her arms crossed. She was leaning against the wall. Beth seemed to be speaking to her earnestly with the way she was standing. It seemed to be a serious conversation, from what I could see,” she said.

Another co-worker said Astley started dating other people in the weeks leading up to her death.

Wayland Police Sgt. William Smith was on patrol the night of the teen’s disappearance. He testified he was assigned to go to Fujita's home to ask about her. Fujita told him he and the young woman who had just broken off a relationship with him had spoken earlier that night.

“I asked him what they talked about and the answer I got was, ‘It was awkward,’” Smith said.

Smith said he pushed for an explanation of awkward. He said the defendant's mother, Beth Fujita, spoke up.

“Mom advised me that Nate and her had been home watching movies together,” Smith said.

Fujita’s lawyer said his client had been diagnosed with a depressive disorder weeks before Astley was found dead.

During opening statements Wednesday, prosecutors said Fujita’s actions were deliberate. They pointed to evidence of a specific search on his computer.

“Does water erase finger prints? I ask you when you hear that not only to think about the implications for what he did, but think about the implications for how his mind was working and what his intentions were,” prosecutor Lisa McGovern said.

Fujita’s attorney said his family has a history of mental disorders and that two family members suffer from schizophrenia.

"Nathaniel said he felt, at that point, he had left his body," defense attorney William Sullivan said. "He didn't know what he was doing, and as a result this horrific act took place."